Multiple sclerosis (MS) is the most common disabling disease of the central nervous system in young adults, hallmarked with walking and mobility issues. However, these difficulties most commonly lead to disability, making driving especially important for running errands or attending medical appointments.
There’s no single answer to whether someone with MS can drive.
Visual acuity issues brought on by visual MS symptoms are the root cause for making MS patients unfit to drive.
A clinician can run a battery of in-office tests to determine whether the further driving evaluation of a patient with MS is necessary or whether they’re fit to drive.
Multiple sclerosis is a progressive disease. That means that patients will eventually face mobility issues. However, as the disease progresses, the person grows more dependent on transportation — to pick up medication or to attend doctor visits. Therefore, the question of whether someone with MS can drive is of utmost importance.
Fitness to drive, i.e., the capability to control a motor vehicle is important for the driver’s safety and the safety of others. Driving is a complex task requiring careful hand-eye coordination. However, numerous MS symptoms, such as visual symptoms and spasticity, among others, may interfere with driving ability — so, the answer is, “It depends”.
From a legal perspective, there is typically no automatic medical probation on one’s license. Additionally, MS is not acute, like dementia or disorders that can cause a lapse in consciousness, such as epilepsy. Therefore, because of different MS types, such as secondary progressive or relapsing-remitting, it’s impossible to determine whether someone with MS can drive.
Science tells us that about 20-40% of people with MS fail on-road driving assessments — mostly due to issues stemming from visual symptoms. In this context, studies have also demonstrated that measuring visual impairment in an office setting via charts or Snellen tests is inaccurate. Furthermore, driving-simulator studies were also unable to clear up whether a patient with MS should be permitted to drive. Therefore, on-road testing is often necessary to make a proper determination, which is time-consuming and not always available.
As such, studies demonstrated that the best predictor of driving ability in MS was found to be far-sighted binocular visual acuity. This helped clinicians better determine which patients were at risk of not being able to drive safely. It also helped them make appropriate referrals for on-road testing and further ophthalmologic testing depending on local laws.
Multiple sclerosis scales and driving
The prognosis of MS is highly individualized, and doctors use numerous scales to track the disease’s progress. Among these, the most commonly used and accepted is the Expanded Disability Status Scale (EDSS), aimed at tracking mobility. Interestingly, studies show that EDSS and similar scales did not predict the driving performance of people with MS. This further demonstrates that this is extremely individualized and depends primarily on visual acuity.
However, two scales, the Stroke Drivers Screening Assessment (SDSA) and useful field of view (UFOV), have been shown to predict the capability to drive in patients with MS. They measure processing speed, visual attention, and central visual processing speed. These are the main symptoms that restrict patients with MS from not being able to drive safely. As most jurisdictions worldwide put the onus of reporting possible unsafe drivers to the appropriate licensing body on clinicians, these scales may be helpful in an office-based elucidation of safe vs. unsafe drivers with MS.
So, unfortunately, there’s no straight answer as to whether a patient with MS can drive or not. A patient with recently diagnosed MS may not be able to drive due to a preponderance of visual symptoms. Meanwhile, a patient that has had MS for over 20 years and can’t ambulate may be allowed to drive because all of their symptoms may be motor related.
Thus, being permitted to drive is evaluated on a case-by-case basis. The most common predictor of fitness to drive is far-sighted visual acuity, and there are possible scales that can be used in the office setting to appropriately guide & refer patients. Patients who feel that their driving ability is compromised should inform their clinician. A medical professional may be able to help delay the progression of MS symptoms preventing the person from driving.